At 01:42 PM 2000-09-25 -0500, Jon Gunderson wrote:
>Al,
>Thank you for your response. If I could summarize some of the main topics
>that I caught from your response.
[...]
>Does this summarize your important requirements for a solution?
>
It was helpful to me; but I want to make another run at summarizing,
myself, here:
What is structural navigation trying to accomplish? What is the user
requirement? So far as I can tell what we should be pursuing here is:
"The user has [some amount of] informed control over what parts of the page
they read."
That is how I would describe the relevant measure of effectiveness. The
rest is 'how.'
Background:
1. In eyes-free mode, there is no such thing as peripheral vision. You
either listen to content, or you don't.
2. In page design for GUI consumption, there are enough pixels so that the
author includes a lot of information that is of secondary interest. The
margins of the graphic canvas tend to attract information that is of
secondary importance to the prime message of this particular page. This
includes the top margin that gets sequenced first in the hypertext
encoding. Typical web pages start with content of secondary interest that
includes a lot of links. Simple tabbing to learn what is in the page
becomes "useless for practical purposes [a.k.a. a P2 failure]" far too often.
3. [Jon on the last call admitted "I don't think the user has a container
model of the content.] The failure of HTML to bind header elements [H1-H6]
explicit containers or ranges of content is often lamented. But for the
eyes-free user, this does not that much matter. There is an alternate
model of the navigable content experience which is like the difference of a
CD over an audio tape. In this content model there is a continuous-stream
"listen to it" process punctuated with navigable alternative staring
points. The lowest level of structural navigation is choosing among these
alternative staring points in the otherwise continuously flowing stream.
Headers are high quality starting point markers, regardless of where the
topic they introduce ends. The decision being made (in this model) is
whether to enter the continuous listening mode at that point or not. When
used in accordance with WCAG 1.0, headers tell you what to expect if you
start reading at that point.
If we think that there is a need for "structural" navigation it indicates
that we recognize that the tabbing sequence often breaks down as an
effective means of getting an overview of the page, and some alternate set
of fewer, more widely spaced starting points are required to give the user
an effective means of controlling where they go and what they read (listen
to).
4. The efficiency of structural navigation is measured by how much time
and effort is spent prior to getting to some segment you actually want to
read. The effectiveness of structural orientation is measured by how well
you can anticipate which of the starting points will be closest to what you
actually want to read.
** non-tentative position
Making it clear that 7.6 and 8.4 are working from the same page, i.e. the
same "User Agent's understanding of the page's content structure" is a
JustDoIt. There is no room for there to be conflicting versions of this
virtual structure and be helping the user. At the model level there is one
such beast.
** tentative positions:
a. One level of page breakdown from the top would meet minimum
requriements, so long as it is reasonably well done. [remember I said
'tentative']
b. In considering what starting points to include or exclude from the
structural navigation options made available to the user, the User Agent
should consider both
(1) breaking the super-unit down into reasonably equal parts as measured by
time-to-speak, and
(2) how well the user agent can quickly explain to the user what to expect
if they start reading at that point.
c. In evaluating the latter, the User Agent should consider both
(1) The availability of an author-supplied natural language identification
associated with this starting point. This includes captions on tables,
headers that just are, the section they are on is not marked, and titles on
horizontal rules if you have nothing better.
(2) The type of element for some types of strong structural significance
such as FORM and FRAME.
But htere is not a_priori precedence between a given element TITLE vs. the
type of another element. All three factors should be considered at once,
including the spacing of the resulting navigation waypoints in time-to-speak.
d. In making navigation to the selected 'major' internal starting points
available to the user, either a generated panel of hypertext linking the
waypoint identification to the starting points, or commands moving among
this set of waypoints and announcing identification as one moves is
acceptable. The user agent may elect either option and meet minimum
requirements.
Al
>
>1. A new checkpoint should be created that would directly address skipping
>over author identified navigation bars (i.e. MAP in HTML).
>
>2. Important elements should be informative and presented through a
>description of what make the elements important (i.e. some elements are
>more important than other elements for navigation and structure)
>
>3. Need to break large documents in to smaller units of information that
>can more easily be digested. The smaller units can be navigated from a
>generated table of contents.
>
>4. Some pages have author supplied tables of contents.
>
>5. Improve linking of checkpoints 8.4 and 7.6, or make part of requirement
>in 8.4 is that this view be a navigation mechanism for the document
>
>Does this summarize your important requirements for a solution?
>
>Jon
>Jon Gunderson, Ph.D., ATP
>Coordinator of Assistive Communication and Information Technology
>Division of Rehabilitation - Education Services
>MC-574
>College of Applied Life Studies
>University of Illinois at Urbana/Champaign
>1207 S. Oak Street, Champaign, IL 61820
>
>Voice: (217) 244-5870
>Fax: (217) 333-0248
>
>E-mail: jongund@uiuc.edu
>
>WWW: http://www.staff.uiuc.edu/~jongund
>WWW: http://www.w3.org/wai/ua
>